Effect of cartilaginous endplates on extruded disc resorption in lumbar disc herniation.

The aim of this study was to investigate the clinicopathologic features of lumbar disc herniation (LDH) with endplate degeneration and the association between cartilaginous fragments and inflammatory response to the herniated disc.LDH often involves hyaline cartilage fragments pulled from the vertebral endplates. Modic changes are closely associated with LDH that contains hyaline cartilage, and cartilaginous endplates seem to affect resorption of the herniated disc.A total of 78 patients who underwent microscopic discectomy between 9 and 16 weeks after an occurrence of LDH were reviewed. Modic changes, disc degeneration, high-intensity zone, and vertebral corner defect were evaluated using magnetic resonance imaging (MRI). Histopathological observations of cartilaginous endplates and inflamed granulation tissue in the herniated disc were made. In cases with inflamed granulation tissue, neovascularization and macrophage infiltration were also evaluated using immunohistochemical analysis.Modic changes were observed in approximately one-third of the patients (26 cases: type 1, 7; type 2, 17; and type 3, 2). Cartilaginous endplates were observed in 32 cases (41%) and in the majority of cases with Modic changes compared with cases without Modic changes (65%, p = 0.001). Although inflamed granulation tissue was observed in 60 cases (77%), no significant differences were detected in patient age and the composition of the herniated material. Immunohistochemical analysis showed that fewer CD34-positive capillaries and CD68-positive cells were found in cases with cartilaginous fragments compared with those without cartilaginous fragments (p < 0.001). In addition, a higher immunoreactivity to CD34 and CD68 was found in herniated discs <25% of whose area was occupied by cartilaginous endplates compared with discs whose area was occupied at 25% or more (p < 0.001).There is an association between LDH with endplate degeneration and cartilaginous herniation, with Modic type 2 predominating. Furthermore, neovascularization and macrophage infiltration, especially if the amount of cartilage is high, are likely to be less frequent in cartilaginous herniation, leading to failure in the spontaneous remission of clinical symptoms

The numbers of neovascularization and macrophage infiltration in patients with LDH containing cartilaginous endplate (<i>n</i> = 25).

<p>The numbers of neovascularization and macrophage infiltration in patients with LDH containing cartilaginous endplate (<i>n</i> = 25).</p

The numbers of neovascularization and macrophage infiltrate in the herniated disc (<i>n</i> = 60).

<p>The numbers of neovascularization and macrophage infiltrate in the herniated disc (<i>n</i> = 60).</p

Cartilaginous herniation with Modic type 2 change.

<p>(A) The inferior endplate of L4 and the superior endplate of L5 show increased signal intensity on both T1-weighted scan. (B) The T2-weighted scan showed increased intensity in the same location. (C) Cartilaginous endplates were present in the herniated disc, along with the annulus fibrosus.</p

MRI and histopathological findings.

<p>MRI and histopathological findings.</p

Relationship between cartilaginous endplate and detailed data of Modic changes.

<p>Relationship between cartilaginous endplate and detailed data of Modic changes.</p

Relationship between clinical features, MRI findings, and histopathological findings.

<p>Relationship between clinical features, MRI findings, and histopathological findings.</p

Composition of herniated tissues.

<p>(A) A herniated mass containing hyaline cartilage from the endplate. (B) CD34-positive capillaries are partly observed in the herniated specimen. (C) CD68-positive macrophages are less frequent. (D) Inflamed granulation tissue is observed in herniated specimens without cartilaginous endplates. (E) CD34-positive capillaries are distributed diffusely in the herniated specimen. (F) CD68-positive macrophages are abundant.</p